PyQT5 QGIS对话框交互

Question

Background: Im trying to use a QT designer form as a QGIS attribute form (which is fine and working) but the code for this doesnt follow any documentation or examples ive been able to find. I did find a little from 2007 which has at least allowed me to get alot working but i feel like its terribly inefficient.

Problem: Getting access to events (closeEvent) from a dialog form within QGIS.

import sys
from PyQt5.QtWidgets import QWidget, QMessageBox, QApplication


class Example(QWidget):

    def __init__(self):
        super().__init__()

        self.initUI()


    def initUI(self):               

        self.setGeometry(300, 300, 250, 150)        
        self.setWindowTitle('Message box')    
        self.show()


    def closeEvent(self, event):

        reply = QMessageBox.question(self, 'Message',
            "Are you sure to quit?", QMessageBox.Yes | 
            QMessageBox.No, QMessageBox.No)

        if reply == QMessageBox.Yes:
            event.accept()
        else:
            event.ignore()        


if __name__ == '__main__':

    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

I got this code from Zetcode Link which im sure would work for standalone of pyqt5 but if i try use this in qgis it crashes the entire application. I believe this is because QGIS is the application and the dialog is under that somehow so the event maybe links to the dialog differently and im not sure how to access that. Does anyone have an idea of how i could access the close event for the dialog thats created using QGIS attribute forms.

Answer 1

You can not use PyQt like you would do with a standalone app, take a look at this: developing-python-plugin

In your code, you are instantating a new QApplication, where your parent application should be QGis; see the QgsInterface class

The pyqgis documentation also recommend the use of the pluginbuilder plugin, which will help you to create a template of your plugin.

Also, be aware that PyQt5 is only supported with qgis 3+. For prior versions, use PyQt4.

Answer 2

Yes, it is working properly, you just avoid the

if __name__ == '__main__':

section and just instantiate the class

ex = Example()